Here's an interactive Addon. I haven't worked on it for a while, and it's only about half done, but I thought people might enjoy playing with it. Be sure to read the readme files. Just about everything in it will react to being clicked-on after you invoke the .celx script.

OMG, Selden, you make an incredibly original thing. I see here many of the addons you made in the past, like Von Braun's ship to Mars etc, that I'm still using in my school courses, but now you show them in such a dynamic way!I'm very pleased for this, and cannot wait to see it completed.Well done and very appreciated, my nephews tomorrow will surely love it.ByeGoofy

VERY impressive, incredible, Selden!!! The add-on is intensively coded in Lua (5.1). But I am wondering when Lua 5.1 has faded out and replaced by Lua 5.2, your add-on Lua code could be no longer compatible, unless Celestia forever uses Lua 5.1.

This is also a worrying issue that has to add onto the future of Celestia: it seems a big hurdle to upgrading Celestia to Lua 5.2.

Lua 5.2 also is obsolete: 5.3 was released in January, 2015. The current version is 5.3.4, released Jan. 30, 2017.

A quick scan of the incompatibilities suggests that the differences are not likely to have a significant impact on Lua programs, at least not what I've written. The implementation inside Celestia might require significant changes, though.

Note, however, that sticking with an older version is not necessarily a bad thing. Lua is used in many "embedded" products, so older versions of Lua have to continue to exist or civilization as we know it would collapse. To put it another way, once a particular computing environment has been designed into a hardware device, it has to continue to be supported for far longer than the software manufacturers would like to admit. For example, the lab where I work has many extremely expensive data acquisition devices which run "no longer supported" operating systems from ROM. Replacing them all is not an option.